Spectrum analyzer – which one to buy in 2025?

[MacIntoshCZ]

My Tektronix 492 stopped working today. I was using it purely as a reference instrument — not for exact measurements, but to get relative values from which I could determine attenuation after applying shielding.
Realistically, I’ll only need spectrum analysis up to around 6 GHz. My main background is in power electronics, but I’ve recently started getting into RF as well. I remember that a Siglent model could be hacked in the past to enable vector network analyzer functionality. If such a modification is still possible, that would obviously be a great bonus. What do you think offers the best value for money?

[Conrad Hoffman]

This is the best time for spectrum analyzers ever! If you have the money, pick whatever Siglent has the features you need. I'm not sure I'd hack one, though if you read the threads here you can find out how. Your needs don't sound difficult, so you could go cheap with a TinySA.
https://www.tinysa.org/wiki/

[Doctorandus_P]

My Tektronix 492 stopped working today.

https://duckduckgo.com/?t=h_&q=Tektronix+492&ia=images&iax=images

That looks like one of the old ones, it still has a CRT.

Realistically, I’ll only need spectrum analysis up to around 6 GHz.

For 6 GHz, scopes with have a simple spectrum analyzer as an extra don't have that bandwidth, so that is not an option.

What do you think offers the best value for money?

I think that's the wrong question. These things have a quite wide range of specificiations, and better specifications cost more. But that said, Siglent seems a pretty safe bed in the "affordable" category.

Or indeed the DIY / gadget market if your budget is really low, the NanoVNA does not go up to 6GHz, but recently there was an article on Hackaday of a VNA (sort of specturm analyzer) up to 15GHz for (approx) USD 300. (I guess that's only BOM cost, I have not looked into details).

https://hackaday.com/2025/04/16/homemade-vna-delivers-high-frequency-performance-on-a-budget/
https://hforsten.com/designing-a-low-cost-high-performance-10-mhz-15-ghz-vector-network-analyzer.html

[rteodor]

There are 3 models of TinySA Ultra: The oldest goes up to 5.4 GHz, the last one (ZS-407) goes to 7.3GHz. 169EUR + VAT at eleshop.

Then you have plenty of money left for a VNA too:
LiteVNA: >6GHz 60-50-40dB range for a bit less money than for an Ultra
LbreVNA: 6GHz 90-100dB range (cca. 600EUR +VAT)

If I remember correctly its Siglent SSA3032X Plus 3.2GHz model that is hackable to 7.5GHz. Cca. 1400EUR + VAT.

[MacIntoshCZ]

I know TinySA, but I think I’d like something with a greater dynamic range. Still, for the price, it's an amazing little device. I think it’s great for students in courses, why not. That DIY version looks interesting, but it’s more for advanced users – I’m not quite there yet. Either way, that guy is a real pro. From what I see, digital spectrum analyzers that go up to 6 GHz cost quite a bit. I already own a NanoVNA – also awesome!

[rteodor]

Just a heads-up about SSA3032X Plus: the newer HW revisions also need a cable inside for the VNA hack to work.

edited in: VNA

[TELCO]

I personally own the Siglent SSA3015X Plus and I am very happy with it. Current price is around $1,295 which I think is an affordable price for all of the features you get with it. Like someone said here it will depend on your needs and budget permitable. I agree that this is the best time to buy a modern SA. Best of luck in your search. 

[Testtech]

What is wrong with the 492? Why not repair it?

[MacIntoshCZ]

What is wrong with the 492? Why not repair it?

I've owned the analyzer for about two years. When I bought it, it almost caught fire after about a week. The input X2 capacitor caught fire. Luckily, I was in the room at the time. What a coincidence it didn't happen overnight while I was asleep. I replaced the capacitor, and it continued to work.

A few days ago, I turned it on — it started up, then the relays inside began switching, and it shut off. After that, a screen with the firmware version and date came up, and then it quietly died. Since then, it hasn't turned on again.

I took it apart and noticed that the X2 capacitor I had soldered had come loose and was lying on the PCB. I'm not sure what it might have shorted out. I quickly tested various diodes and looked to see if anything had burned out, but I couldn't find any visible damage anywhere.

[G0HZU]

The Tek 492 spectrum analyser was never a great instrument so I would recommend an upgrade rather than spend time and money on repairing it.

These analysers were relatively poor 35 years ago. Today they are very dated in terms of performance and capability. They probably have the most appeal to collectors or maybe radio hams who need a very basic analyser (with limited frequency accuracy, limited dynamic range and limited amplitude accuracy) that can cover up to about 20 GHz. For everyone else this instrument will be quite awful to use compared to modern offerings. The Siglent analysers only cover up to a few GHz but I'd expect them to totally outclass the Tek 492 within their frequency range. Not even a contest. Not even close.